Polyalkylene carbonate is a polymer material useful for being used as a packing material, a coating material, and the like. In order to prepare the polyalkylene carbonate, a method of preparing the polyalkylene carbonate from an epoxy compound and carbon dioxide is known, wherein the method has an environmentally friendly high value in that phosgene being a noxious compound is not used and carbon dioxide is capable of being obtained in the air. Accordingly, many researchers have developed various types of catalysts in order to prepare polyalkylene carbonate from the epoxy compound and the carbon dioxide.
Since 2000, the development has significantly advanced in fields for developing the catalysts. Among them, development of a binary catalyst system using a mixture of a (Salen)Co compound or a (Salen)Cr compound [H2Salen=N,N′-bis(3,5-dialkylsalicylidene)-1,2-cyclohexanediamine)], and an onium salt such as [R4N]Cl or PPNCl (bis(triphenylphophine)iminium chloride) or a base such as amine or phosphine is representative. With respect to the binary catalyst system of the (Salen)Co compound, a mechanism in which epoxide is coordinated to the metal center having a lewis acid group to be activated, and nucleophilic-attack is performed thereon by carbonate anions derived from an onium salt or a bulky amine base was suggested.
Meanwhile, Chinese Patent Application Publication No. 101412809 discloses a method of synthesizing a salen-typed Co complex catalyst including one or two dimensionally large neutral organic base group(s) (TBD) and a method of preparing polyalkylene carbonate by copolymerizing an epoxide compound and carbon dioxide by using the same.
However, in the above-mentioned methods, copolymerization only using a bulk polymerization is disclosed. In the bulk polymerization, a catalytic activity is excellent; however, after the polymerization is completed, it is difficult to perform post-treatment processes such as control of side reactions in self-polymerization of epoxide, cleaning of a reactor, and removal of metal residue in the polymer, such that scale up is not easily conducted.